Seismic exploration involves surveying subterranean geological media for hydrocarbon deposits. Some surveys are known as “marine” surveys because they are conducted in marine environments. However, “marine” surveys may be conducted not only in saltwater environments, but also in fresh and brackish waters. In one type of marine survey, called a “towed-array” survey, an array of seismic sensor-containing streamers and sources is towed behind a survey vessel.
A survey typically involves deploying seismic source(s) and seismic sensor(s) at predetermined locations. The sources generate seismic waves, which propagate into the geological medium creating pressure changes and vibrations. Variations in physical properties of the geological medium change properties of the seismic waves, such as their direction of propagation and other properties. Parts of the seismic waves reach the seismic sensors. Some seismic sensors are sensitive to pressure changes (hydrophones), others to particle motion (e.g., geophones), and industrial surveys may deploy only one type of sensor or both. In response to the detected seismic waves, the sensors generate corresponding electrical signals and record them in storage media as seismic data.
Well-log data can also be used to better understand a geological medium. Well-log data is obtained by placing a sensor (e.g., an electrical sensor, porosity sensor, gamma ray sensor, nuclear magnetic resonance (NMR) sensor, and/or others) in a well that has been, or is being drilled, and measuring various properties along the path of the well using the sensor.
One goal of seismic exploration is to create an accurate image of the underground geological structure using the seismic data collected from the region and an earth model that represents a geomechanical state of the same region. But current earth models lack the level of detail, resolution, and complexity needed for modern hydrocarbon exploration.